Mass Spectrometry: A Tool for Enhanced Detection of Hemoglobin Variants

Abstract

BACKGROUND:More than 900 hemoglobin (Hb) variants are currently known. Common techniques used in Hb analysis are electrophoretic and chromatographic assays. In our laboratory, we routinely apply chromatographic methods. To ascertain whether Hb variants are missed with our procedures, we additionally analyzed all samples with mass spectrometry (MS).

Electrospray Ionization Mass Spectrometric Analysis of the Globin Chains in Hemoglobin Heterozygotes Can Detect the Variants HbC, D, and E

“…We would like to point out that 2 recent articles in this journal about human hemoglobin (Hb) analysis (1,2 ) give the false impression that variant globin chains with Ͻ6 Da mass difference from normal cannot be detected in heterozygotes by electrospray ionization mass spectrometry (ESI-MS). Kleinert While we agree that ESI-MS cannot detect the zero mass change mutations (Lys7Gln and Leu3 Ile), we maintain it is not necessary to resolve the variant and normal globin chains in heterozygotes to detect variants that differ in mass from normal by Ϯ1 Da (Glu7Lys, Glu7Gln, Asp7Asn, Asn3 Ile).…”

“…As a screening test for detecting decreased GFR, cystatin C has fewer inherent limitations than serum creatinine. Moreover, unlike creatinine, cystatin C reflects renal function independent of age, sex, height, and body composition (1 ). Formulae have been developed allowing estimation of GFR based on cystatin C (1 ).…”

The use of LC tandem mass spectrometry as part of a workflow for the screening and identification of hemoglobin variants. Characterization of Hb Ullevaal as an example

“…The deconvolution of the multiply charged globin spectrum yields a single mass peak of 15,854 m/z which corresponds to a difference of −14 m/z compared to the wild type β chain (Figure 4). Only 40 of 861 possible single point mutations of β-globin are expected to show this pattern [8].…”

“…While about 2/3 of the variants do not show a charge difference to the wildtype entity, >95% of them differ in hydrophobicity ( Figure 1) [8]. This implies that screening procedures relying only on differences of the isoelectric point probably will be insensitive to 2/3 of possible variants.…”

Hemoglobin Varyantlarının Ölçümünde Interlab-G26 Elektroforezi ve Primus Ultra2 HPLC Yöntemlerinin Karşılaştırılması

“…Hemoglobinin globin zincirindeki aminoasit dizisindeki değişiklikler ise hemoglobinopati olarak isimlendirilir ve en yaygın olarak görülen hemoglobin varyantı globin zincirinde 6. pozisyonda glutamik asit-valin değişimi ile karakterize hemoglobin S (Hb S)' tir (3,4). Bugüne kadar 900' ün üzerinde hemoglobin varyantı tespit edilmiştir (5). Hemoglobinopatilerin tespiti hem anemik kişilerin değerlendirilmesinde hem de evlilik öncesi çiftlerin koruyucu hekimlik açısından taranmasında klinik açıdan oldukça büyük önem taşır.…”